Tracheal catheters are used to assist patient breathing during and after medical procedures until they are able to breathe successfully on their own and be removed from assisted breathing. One type of tracheal catheter, the endotracheal tube (ET tube), is inserted through the mouth of a patient and guided past the vocal cords and glottis into the trachea. Once the patient is intubated, the ET tube is connected to ventilators or respirators for mechanical ventilation of the lungs. Another type of tracheal catheter, the tracheostomy tube (trach tube), is inserted through a stoma in the throat, directly into the trachea and may also be connected to a ventilator. The ventilator unit is connected to a hose set; the ventilation tubing or tubing circuit, delivering the ventilation gas to the patient as a ventilating system.
Removing secretions from the trachea-bronchial tree is an integral part of the care given to patients who are intubated and receiving mechanical or other artificial ventilation. Secretions can be excessive in some respiratory disorders and constitute a serious threat to the patient having such respiratory disorders. The presence of a tracheal catheter is a hindrance to the patient's efforts to clear secretions through natural coughing. In current medical practice, suction catheters are inserted into the lungs to clear such secretions from the patient's airway by suctioning.
Suctioning may be performed using an “open” or “closed” system. In the open system, the suction catheter is merely a flexible plastic tube that is inserted into the tracheal catheter ventilating lumen with a source of suction connected to the proximal end of the suction catheter. The suction catheter is advanced as far as desired and suction is applied to remove secretions. Anything that the suction catheter touches before entering the lumen must be maintained in a sterile condition so a “sterile field” must be created on or next to the patient. The suction catheter must be carefully handled after it is used since it will be coated with the patient's secretions. In contrast, in the “closed” system, for example that disclosed in commonly owned U.S. Pat. No. 4,569,344, a device 10 which may be used to suction secretions uses a suction catheter 12 enclosed within a generally cylindrical plastic sleeve 14 to eliminate or minimize contamination of the suction catheter prior to use (FIG. 1). This is generally referred to as a “closed suction catheter” and may be available under the trade names TRACH CARE® from BALLARD® Medical Products and KIMVENT®, all from Kimberly-Clark Corporation. As the patient requires artificial removal of secretions, the suction catheter 12 may be advanced through one end of the plastic sleeve 14, through a connecting fitting 16, into the tracheal catheter and, if desired, into one of the main bronchi of the patient. The other, proximal end 17 of the suction catheter 12 is attached to a source of suction 19. Suction is applied to the proximal end 17 of the suction catheter 12 using a finger controlled valve 18 to remove the secretions. The other bronchus may likewise be aspirated. Secretions are thus drawn into the lumen of the suction catheter 12 and removed and the system remains closed. The suction catheter 12 is subsequently withdrawn from the tracheal catheter and back into the plastic sleeve 14 to keep the circuit closed. Closed suction systems are generally preferred by healthcare providers since the medical care provider is better protected from the patient's secretions. Closed suction systems are also easier and quicker to use since a sterile field need not be created each time the patient must be suctioned, as is required in open suction systems.
One drawback to the closed suction catheter system described above has been the over-withdrawal of the suction catheter 12 into the plastic sleeve 14. If a user pulls the suction catheter too much, the suction catheter 12 can slip out of the proximal end of the connecting fitting 16. When this occurs the seal between the suction catheter 12 and the connecting fitting 16 is lost and pressurized air from the ventilator enters the plastic sleeve 14, expanding it and possible rupturing it. A failure of the plastic sleeve 14 can expose the medical personnel in the area to the airborne secretions of the patient. Such a failure can also reduce ventilator efficiency for the patient, leading to patient complications and even death.
In order to prevent the suction catheter from pulling out of the connecting fitting, various “stops” have been proposed. Making the distal end of the suction catheter too large to fit through the connecting fitting, for example, has been investigated but not adopted since a strong caregiver may still be able to over-withdraw the suction catheter and in so doing, break off a piece of the suction catheter that could fall into the respiratory tract of a patient.
U.S. Pat. Nos. 5,598,840 and 5,088,486 contain a cursory reference to a single lanyard, cord or tether running between the two ends of the plastic sleeve. Neither reference, however, explains how such a tether may be installed or attached or what it should be made from. U.S. Pat. No. 7,188,623 describes press-fitting two parts of each end of a closed suction catheter together and placing between the press-fit parts a single, preferably monofilament tether, thus placing the tether in a pinch hold to resist the force exerted by an attempted over-withdrawal. Unfortunately, it has been quite surprisingly found that using press-fit parts to hold a tether is insufficient. The average health care provider can easily apply enough force to pull an end of the tether from the pinch of the press-fitted parts and this requires no more than ordinary strength. Another surprise found was the degree to which monofilament stretches with the application of moderate force, making such a material unsuited for this use.
Lastly, in manufacturing terms, the cutting of a length of cord and attaching it to each end of a closed suction catheter results in the addition of the tolerances allowed at each connection. This adding of manufacturing tolerances, sometimes referred to in the art as “stack up”, can result in the suction catheter tip being some distance from the correct position when it is in the withdrawn position, even if each individual component of the system is within its manufacturing tolerances.
It would be desirable to have a system for prohibiting the over-withdrawal of the suction catheter from the connecting fitting without the drawbacks of the prior art techniques, that distributes the forces more evenly and that is relatively simple and cost effective to produce.